Converting an ATX computer power supply to a 12 volt DC Power source
By Fearless Fabricator on Saturday, December 6th, 2008
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I built this to provide current for electrolytic etching of copper and brass, but it can be used to power electronic projects as well. It is a simple procedure, for those with basic electrical skill and understanding of the safety practices needed for working with power supplies.
WARNING: If you read this and don’t understand any part of it, you don’t have the base knowledge needed to attempt this project safely.
WARNING: unplug unit before attempting anything!
WARNING: power supplies can hold a charge of electricity!
WARNING: If you don’t know or don’t think electricity can kill you dead, DO NOT PROCEED!
Necessary parts:
10 ohm 10 watt resistor
SPST switch
Electrical tape and or heat shrink tubing
Optional parts:
LEDs
Resistors (for 20 to 25 ma 84 to 100 ohms ¼ watt should work fine)
Now down to work.
Remove ATX power supple unit from computer if not all ready separate, keeping wires as long as possible but remove the connectors. The power supply has a number of checks or safeties that keep it from working at this point. Next remove the access cover, but it is not necessary to remove the circuit board from the power supply housing. Sort wires so you have set aside the following:
2 red wires (only one if you are skipping the LEDs)
1 yellow
4 black (only three if you are skipping the LEDs)
1 green
1 brown (if brown/orange pair is present)
1 orange (if brown/orange pair is present)
Clip all other wires at circuit board, if longer cover the ends with electrical tape or shrink tube.
Brown and orange are connected together permanently for the 3.3 volt sense to enable the power supply to work. (If there’s no brown/orange pair, ignore this step.)
Next the 5 volt rail needs a load for the power supply to operate properly. The 10 ohm 10 watt resistor provides this load when connected between a red and a black wire. This baby heats up a bit so it needs to be mounted in a way that dissipates that heat, like in the air flow of the fan or on a heat sink.
The power on/off is made by connecting the SPST switch between the black and the green wires. Insulate all bare connections. LED with a resistor can be hooked in parallel between a set of red and black wire.
The two remaining black wires are twisted together. Now when activated there should be 12 volts dc between the yellow and paired black.
12 volt power supply
Mount, jank, decorate, and make safe your new power supply.
LED exact resistors needed can be calculated at http://led.linear1.org/1led.wiz
Max power output can be figured with the equation Watt = volts x amps, minus say 10% (just of the top of my brain) for 5volt load, LEDs and loss. These are modifications the instructions from http://www.vonslatt.com/bus-tron.shtml
Cases for ATX power supplies.
- Converting an ATX computer power supply to a 12 volt DC Power source
- Cases for ATX power supplies.
Tags: 12, atx, computer, construction, dead, diy, electricity, electronics, etching, fabricator., fearless, hedwig, kill, led, modification, P, phinneus, power, re-purpose, re-use, resistor, steampunk, steampunk fashion, supply, volt, von, vonHedwig, vonslatt, warning
